This invention relates to heater systems for injection molding equipment, particularly, the invention relates to such systems with heaters which require periodic replacement.
Plastic injection molding utilizes steel molds which are separable and have cavities into which molten plastic resin is injected. The pressures that the molds are subjected to can be extreme and thus the mold components are often massive to support such pressures. Often the nozzles which are utilized to inject the plastic resin into the mold cavities have ancillary heating to properly maintain the molten resin temperature. The ancillary heating is provided by heater coils or cartridges placed on or at the nozzles. In that these nozzles and ancillary heaters are positioned within the mold parts, channels, pipes, and tubing are provided thru the mold parts to provide electrical power to the heaters. The channel, tubing, and pipe sizes are kept to a minimum to reduce tooling costs and preserve the mold strength. The heaters conventionally utilize magnesium wire and operate at 240 volts. Such heaters periodically burn out.
The channels, pipe and tubing are typically electrically conductive so that the connection components must be insulated. The limited space, the high current requirements, and the necessity of maintaining the integrity of the electrical path, make conventional friction electrical connections, such as bullet and spade connectors unsuitable for these applications. Thus in the conventional system, connections between the heaters and conductor wires which run thru the mold parts are brazed or permanently crimped. When the heater burns out, the heater and the connecting wires has to be pulled through channels, pipe or tubing. New wires then need to be fished through the channels, pipe, or tubing. Alternately, the wires must be cut and rebrazed or new non-reusable crimp connectors installed. This is a time consuming process and can result in very expensive downtime for the injection molding equipment.